A barometer measures atmospheric pressure; a baroreceptor is one of a set of nerve endings that monitor changes in blood pressure; barotrauma is damage to the ear caused by changes in air pressure, as experienced during air travel or deep-sea diving; a barostat (Greek statos, standing), is a device that maintains constant atmospheric pressure in a closed vessel. The bary- equivalent is less common; examples are barycentric, relating to a centre of gravity, and barysphere, the dense interior of the earth, under the lithosphere.